Co metallization for CA/CB contacts is key for advanced technology node and beyond. In particular, Co has a void-free gap fill capability comparable with traditionally used tungsten (W), but offers a low resistance gain compared to W. However, known Co chemical mechanical planarization (CMP) processes have limited ability to achieve a recess-free Co CA/CB formation with Co plating. In addition, current W CA schemes are not compatible with leading post-etch cleaning processes. As illustrated in FIG. 1A (cross-sectional view), a titanium (Ti) and titanium nitride (TiN) liner 101 is formed on the side and bottom surfaces of trenches 103 and over the interlayer dielectric (ILD) 105 that is formed on the substrate 107. The Ti/TiN liner 101 is then annealed by a dynamic surface annealing (DSA) process. Thereafter, a Co liner 109 is formed over the Ti/TiN liner 101 by chemical vapor deposition (CVD). A Co plating layer 111 is then formed in each trench 103 and over the Co liner 109. Adverting to FIG. 1B, a bulk and buff CMP process is performed to planarize the Co plating layer 111 down to the ILD 105 and to remove the Ti/TiN liner 101 and Co liner 109, respectively, from over the ILD 105. However, during the CMP process, the Co liner and plating layer 109 and 111, respectively, are recessed prior to the formation of a silicon carbon nitride (SiCN) capping layer (not shown for illustrative convenience).
A need therefore exists for methodology enabling the formation of Co-based CA/CB contacts without subsequent Co recess or incompatibility with leading post-etch cleaning processes and the resulting device.